Additive for electrolyte, electrolyte, and electrochemical device

1 . An electrolyte, comprising a lithium salt, an organic solvent, and an additive comprising:

a compound represented by a formula (I):

wherein R 1 , R 2 , R 3 , and R 4 are identical to or different from each other, and are independently selected from a group consisting of hydrogen, halogen, substituted or unsubstituted C 1 -C 20 alkyl, and substituted or unsubstituted C 6 -C 18 aryl, and wherein a substituent of the substituted or unsubstituted C 1 -C 20 alkyl or the substituted or unsubstituted C 6 -C 18 aryl is halogen, C 1 -C 20 alkyl, or C 6 -C 18 aryl;

wherein denotes a single bond or a double bond; and

wherein n is 1.

2 . The electrolyte of claim 1 , wherein a concentration of the additive in the electrolyte is 1.0 wt % to 3.0 wt %.

3 . The electrolyte of claim 1 , wherein the lithium salt is at least one selected from a group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium difluoro(oxalato)borate, lithium difluorobis(oxalato)phosphate, and any combination thereof.

4 . The electrolyte of claim 1 , wherein a concentration of the lithium salt in the electrolyte is 0.8 mol/L to 1.2 mol/L.

5 . The electrolyte of claim 1 , wherein the organic solvent is at least one selected from a group consisting of carbonate ester, carboxylate ester, fluorocarboxylate ester, and any combination thereof.

6 . The electrolyte of claim 5 , wherein the carbonate ester is at least one selected from a group consisting of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethylmethyl carbonate, butylene carbonate, methylpropyl carbonate, and any combination thereof.

7 . The electrolyte of claim 5 , wherein the carboxylate ester is at least one selected from a group consisting of ethyl formate, ethyl acetate, propyl acetate, butyl acetate, propyl propionate, butyl propionate, ethyl butyrate, methyl formate, ethyl propionate, and any combination thereof.

8 . The electrolyte of claim 5 , wherein the fluorocarboxylate ester is at least one selected from a group consisting of ethyl fluoroformate, ethyl fluoroacetate, propyl fluoroacetate, butyl fluoroacetate, ethyl fluoropropionate, propyl fluoropropionate, butyl fluoropropionate, ethyl fluorobutyrate, methyl fluoroformate, and any combination thereof.

9 . The electrolyte of claim 1 , further comprising a film-formation additive which is at least one selected from a group consisting of fluoroethylene carbonate, 1,3-propanesultone, 1,4-butanesultone, vinylene carbonate, and any combination thereof.

10 . The electrolyte of claim 9 , wherein a concentration of the film-formation additive in the electrolyte is 0.2 wt % to 4.0 wt %.

11 . An electrochemical device, comprising:

a cathode comprising a cathode current collector and a cathode active material layer disposed on a surface of the cathode current collector;

an anode comprising an anode current collector and an anode active material layer disposed on a surface of the anode current collector;

a separator disposed between the cathode and the anode; and

the electrolyte of claim 1 .

12 . The electrochemical device of claim 11 , wherein the electrochemical device is a lithium battery.

13 . The electrochemical device of claim 12 , the lithium battery is a lithium ion battery or a lithium metal battery.